Here’s a self-improvement tip that I’ve come up with and found helpful. It works particularly well with bad habits, which are hard to fix using other self-improvement techniques as they’re often unconscious. To take one example, it’s helped improve my posture significantly.

1. List your bad habits. This is a valuable exercise in its own right! Examples might include bad posture (or, more concretely, crossing your legs), mumbling, vehicular manslaughter, or something you often forget to do.
2. Get in the habit of noticing when they occur, even if it’s after the fact. You can regularly try remembering whether they have at a convenient time for you, such as at lunch or in the evening. Ideally you should try to notice them soon after they occur however, for reasons that will become clear.
3. Come up with a punishment. The point of this is not to create an incentive not to lapse (you could experiment with that, but I’m not sure whether it will work, as bad habits are rarely consciously chosen). Instead, it’s to train yourself by Pavlovian conditioning - training “system one”, in Daniel Kahneman’s terms. Examples of punishments would be literally slapping yourself on the wrist, pinching yourself, or costing your HabitRPG character health points.